Commercial Mortgage Loans, Subordinate Loans and Other Lending Assets, Net - Schedule of Activity Relating to Loan Portfolio (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Principal Balance
Principal value, beginning balance	$ 7,134,992
New loan fundings	2,183,157	$ 955,328
Principal value, ending balance	8,342,902
Specific CECL Allowance
Specific provision for loan loss, beginning	(30,836)
Specific provision for loan loss, ending	(39,257)	(342,500)
Carry Value, Net
Payments to Fund Commercial Mortgage Loans	2,183,157	955,328
Realized loss on investment	(7,436)	(128,191)
General CECL allowance	(39,257)		$ (30,836)
Carrying value, net	8,303,645		$ 7,145,356
Commercial Mortgage and Subordinated Portfolio Segment
Principal Balance
Principal value, beginning balance	7,550,410
New loan fundings	2,183,157
Add-on loan fundings	701,538
Loan repayments and sale	(2,057,725)
Gain (loss) on foreign currency translation	353,903
Realized loss on investment	(7,436)
Amortization of fees	4,785
Principal value, ending balance	8,728,632
Deferred Fees/Other Items
Deferred fees/other items, beginning	(31,718)
Gain (loss) on foreign currency translation	(1,329)
Deferred fees and other items	(36,912)
Amortization of fees	19,229
Deferred fees/other items, ending	(50,730)
Specific CECL Allowance
Specific provision for loan loss, beginning	(342,500)	$ (193,000)
Specific provision for loan loss, ending	(335,000)
Carry Value, Net
Carrying value, beginning balance	7,176,192
Payments to Fund Commercial Mortgage Loans	2,183,157
Add-on loan fundings	701,538
Loan repayments	(2,057,725)
Gain (loss) on foreign currency translation	352,574
Realized loss on investment	(7,436)
Decrease in Specific CECL Allowance	7,500
Deferred fees and other items	(36,912)
Amortization of fees	24,014
Carrying value, ending balance	$ 8,342,902

Financing receivable, excluding accrued interest, after specific allowance for credit loss.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing receivable loan decrease to specific credit loss allowance net.

+ References

No definition available.

+ Details

Name:	ari_FinancingReceivableLoanDecreaseToSpecificCreditLossAllowanceNet
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Loan portfolio deferred fee amortization.

+ References

No definition available.

+ Details

Name:	ari_LoanPortfolioDeferredFeeAmortization
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Loan portfolio deferred fees other items.

+ References

No definition available.

+ Details

Name:	ari_LoanPortfolioDeferredFeesOtherItems
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Loan portfolio deferred gain loss foreign currency translation.

+ References

No definition available.

+ Details

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Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Loan and Leases Receivable, Deferred income [Roll Forward]

+ References

No definition available.

+ Details

Name:	ari_LoanandLeasesReceivableDeferredincomeRollForward
Namespace Prefix:	ari_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Loan and Leases Receivable, Gross [Roll Forward]

+ References

No definition available.

+ Details

Name:	ari_LoanandLeasesReceivableGrossRollForward
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Loan and Leases Receivable, Net [Roll Forward]

+ References

No definition available.

+ Details

Name:	ari_LoanandLeasesReceivableNetRollForward
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Loans and Leases Receivable, Gain (Loss) on Sales, Gross

+ References

No definition available.

+ Details

Name:	ari_LoansAndLeasesReceivableGainLossOnSalesGross
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Loans and Leases Receivable, Net, Realized Gain (Loss) On Investment

+ References

No definition available.

+ Details

Name:	ari_LoansAndLeasesReceivableNetRealizedGainLossOnInvestment
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Loans and Leases Receivable, Deferred Income, Amortization

+ References

No definition available.

+ Details

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Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Loans and Leases Receivable, Deferred Income, Period Increase

+ References

No definition available.

+ Details

Name:	ari_LoansandLeasesReceivableDeferredIncomePeriodIncrease
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Loans and Leases Receivable, Gross, Foreign Currency Gain (Loss)

+ References

No definition available.

+ Details

Name:	ari_LoansandLeasesReceivableGrossForeignCurrencyGainLoss
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Loans and Leases Receivable, Gross, Paid-in-Kind Interest, Loan Commitment and Origination Fees, and Discounts or Premiums, Amortization

+ References

No definition available.

+ Details

Name:	ari_LoansandLeasesReceivableGrossPaidinKindInterestLoanCommitmentandOriginationFeesandDiscountsorPremiumsAmortization
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Loans and Leases Receivable, Net, Foreign Currency Gain (Loss)

+ References

No definition available.

+ Details

Name:	ari_LoansandLeasesReceivableNetForeignCurrencyGainLoss
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Mortgage Loans on Real Estate, Commercial and Consumer And Financing Receivable, Net

+ References

No definition available.

+ Details

Name:	ari_MortgageLoansOnRealEstateCommercialAndConsumerAndFinancingReceivableNet
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Payments to fund commercial mortgage loans.

+ References

No definition available.

+ Details

Name:	ari_PaymentsToFundCommercialMortgageLoans
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Payments to purchase loans add on fundings.

+ References

No definition available.

+ Details

Name:	ari_PaymentsToPurchaseLoansAddOnFundings
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Proceeds from collection of mortgage loans.

+ References

No definition available.

+ Details

Name:	ari_ProceedsFromCollectionOfMortgageLoans
Namespace Prefix:	ari_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

+ References

No definition available.

+ Details

Name:	us-gaap_AllowanceForLoanAndLeaseLossesRealEstate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

Name:	us-gaap_AllowanceForLoanAndLeaseLossesRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of fee received for commitment to originate or purchase financing receivable where likelihood of commitment being exercised is remote, to be recognized as service income.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481598/310-20-45-2

+ Details

Name:	us-gaap_FinancingReceivableDeferredIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Details

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